Now this is actually from Indigo Starfish which handle most of Amazon's entertainment products. I know that 3rd party sellers are a no no but Indigo starfish is just a branch of Amazon (i.e. not second hand or dodgy).
Brilliant series which includes all episodes. This is the cheapest that it's ever been.
I've benn waiting for ages for this to drop but now I've ordered.
Top 3 RetailersView all → Price
1 Buy from Amazon UK £17.97
2 Buy from The Hut £28.85
3 Buy from Zavvi £28.85
Hope it helps